1. Field of the Invention
This invention relates generally to grain dryers, and more particularly to a method and apparatus for unloading grain from grain dryers after it has been dried.
2. Description of the Related Art
Continuous flow tower grain dryers such as those shown in U.S. Pat. Nos. 4,149,844 and 4,249,891, which are incorporated herein by reference, generally have a column which goes completely around the dryer for receiving grain by gravity therethrough. Such dryers have a plenum divider which can determine a heat suction and a cooling suction so as to force cool air through the grain after it has been heated with hot air, for example. These dryers preferably have three modes. There can be (1) pressure heat, vacuum cool, (2) pressure heat, pressure cool and (3) full heat. It is desirable to have a tower dryer which has all three modes, but such is not necessary if a user only desires to use one or two of such modes.
To unload the grain from a continuous flow dryer of the aforementioned type, there have been sweep augers which rotate around the circumference of the floor which pull grain to a center takeaway auger and then through a discharge auger. This auger-type unloading system is expensive and requires maintenance. The auger-type unloading system also causes some reduced quality of the grain being moved, with some damage to the grain from the augers resulting in an economic loss.
In prior art sweep augers often evacuate grain faster than the void gets filled. This causes a hammering effect which stresses the metal sheets of the dryer.
Consequently, there is a need for an improved grain unloading system and method for a continuous flow grain dryer to overcome the disadvantages of the prior art.